11.15 Oxygen Flashcards
At what altitude does the usable oxygen half?
18,000 feet (5480 m)
What is the cabin altitude of aircraft when it is cruising?
8,000 feet
How does lack of oxygen affect humans at :
a) 10,000 ft
b) 14,000 ft
c) 15,000 - 20,000 ft
a) faster breaths to compensate for lack of oxygen
b) exhaustion and sleepiness
c) loss of concentration, partial memory loss, muscle ache, loss of judgement
Why is oxygen used on aircraft different to others used on the ground?
Aviators breathing oxygen is dry, moisture in normal oxygen would freeze
What is important about tooling when working on oxygen systems?
Must be clean and oil free
What does the crew oxygen system supply to?
Cockpit crew only
Where are oxygen bottles stored?
Lower deck
What are the typical materials that oxygen bottles are made of?
Steel alloy or Kevlar (composite)
What colour are oxygen bottles on aircraft?
Dark Green
At 21 degrees C what is the maximum capacity of an oxygen bottle?
3200
Where can the actual bottle pressure be found?
Direct reading pressure gauge
What information would you need to determine how full the bottle is? [2]
- Actual bottle pressure and temperature
- Referral to chart
Where would an over pressure indication be found?
Near the oxygen filler port
How are the lengths of high pressure lines reduced in an oxygen system?
Pressure regulator located near the oxygen bottle
When does the oxygen begin to flow in crew oxygen masks?
When the mask is removed from the storage box
What does the crew mask consist of? [4]
- Harness
- Face piece
- Diluter demand regulator
- Microphone
What are the 3 operating modes of the diluter demand regulator?
- Normal
- 100% oxygen
- Emergency
At what altitude will passenger oxygen masks deploy automatically?
14,000ft
What are the 2 ways oxygen is supplied to the system?
- Chemical system
- Gaseous system
What does a thermal compensator do?
Distributes the heat that may occur during recharging
What does a pressure reducer do?
Reduces the pressures leaving the bottle to an intermediate pressure
If there are more than 1 oxygen bottle, what happens to the indications on the flight deck?
The pressure is averaged between the bottle by a voltage averaging unit
How can the pilots oxygen masks be tested?
Press to test and reset lever without taking the mask out of the stowage box
Where are the passenger oxygen masks located?
The passenger service units
How is the passenger oxygen system activated? (2)
- automatically by pressure switch
- manual on flight deck if pressure switch fails
What can be used for maintenance to open a single PSU containing the passenger oxygen masks without activating the whole system?
A special tool
How does the chemical supply system operate?
The doors operate electrically, dropping masks, oxygen will only flow when the masks are pulled where the oxygen generation process starts
What happens when the pin pulled from the oxygen generator?
Striker triggers a chemical thermal reaction inside the generator
What is the oxygen generator filled with?
Sodium chlorate
How is oxygen generated?
High temperature decomposition of sodium chlorate
How does an oxygen generator indicate that it has been used?
Heat generated changes the colour of the indicator on the side of the bottle
In a gaseous supply system, where is the oxygen supplied from?
oxygen bottles, similar to those used in the crew system
In the gaseous oxygen system, what does a flow control unit do? (4)
- provide a shut off function when not in use
- activate the system
- produce the pressure push to open the PSU’s
- reduce the intermediate oxygen pressure to an adequate level for breathing
What is used to transport the pressure push?
Ring line
How do the PSU’s open?
High pressure oxygen flows for a few seconds moving the diaphragm and moving a plunger downwards.
This moves the latch plate and hooks to the left,
Opening the door
What need to be done before oxygen will flow to the masks?
They need to be pulled and tightened by at least one lanyard, pulling a pin
Other than crew and passenger oxygen systems, what is the other type?
Portable oxygen system
Where can portable oxygen equipment be located?
Flight deck and near exits in passenger compartments
What is the intended use of a portable oxygen bottle?
For emergency and first aid use
What is the maximum filling pressure of a portable oxygen bottle?
1800 psi
What components does the cylinder head of the portable oxygen bottle consist of? (6)
- manual shut off valve
- pressure gauge
- frangible disk for over pressure relief
- pressure regulator reducing oxygen pressure to suitable levels
- built in relief valve In case pressure regulator fails
- filling valve allows oxygen bottle to be filled
What do smoke hoods provide protection against?
Eyes and respiratory system for crew,
Prevent inhalation of smoke and noxious gases
What does the smoke hood consist of? (3)
- the hood itself
- inner mask
- oxygen generator
What two types of masks are used with portable oxygen bottles?
- Full face smoke mask
- continuous flow oxygen masks (first aid purposes)
